A collection of useful sailing, sail trimming and news items from OneSails GBR

Thursday, 16 April 2015

OneSails GBR Racing Spinnakers

The sail that is
undergoing the most significant development today is the spinnaker. With the
help of better fabrics and ever improving sailmaking technology, spinnakers are
more efficient both downwind and also closer to the wind with angles as close
as 45° apparent being possible in some cases.

The
optimisation of a particular spinnaker or inventory is as much to do with
subtleties in shaping as it is for overall area. OneSails make a broad range of
high performance spinnakers for racing boats, symmetric and asymmetric and it
is important for the owner that every sail is customised for a particular boat
with specific angles and windspeeds in mind in order to give truly superior
performance.

It wasn’t that long
ago that a typical 3 sail spinnaker inventory consisted of a ‘light runner’ (0.5oz),
an ‘A/P’ (0.75oz) and a small flat ‘heavy’ (1.5oz). The cloth weights that were
used to describe these sails bore little resemblance to the actual weights.
Nowadays many more cloth weights are available with perhaps as many as 10
different weights available between 0.4oz and 1.5oz. The cloths are also available
in different styles each of which will be more or less appropriate to a given
end use.

Towards the end of
the 1990’s many boats began replacing their traditional symmetric flat heavy
spinnakers with ‘mini reacher’ asymmetrics, more commonly known as A5’s. These
quickly developed a reputation as a real utility sail and were able to point
higher than the other symmetrics in light airs, were better at beam reaching in
moderate airs and could still be flown off a conventional pole as a ‘chicken
chute’ in heavier airs. Since then asymmetric development in particular has
progressed rapidly and nowadays it is commonplace for most symmetrically rigged
boats to also carry an asymmetric or two to cater for particular conditions.

In recent seasons
Code Zero’s have become very popular especially on the more modern boats that
carry relatively small non-overlapping headsails. These boats are often
underpowered in lighter airs and on beam reaches that are too close to fly a
conventional chute. Here the Code Zero comes into its own; in very light airs,
4-5 kts TWS for example, a boat with a Code Zero will point virtually as high
as a boat with a conventional headsail but with much more area and a far better
VMG. As with the A5 mentioned above, the Code Zero is also very useful at
broader angles in more moderate airs when the boat would be over pressed when
flying a full sized spinnaker.

The graphics below
provide an indication as to how various spinnakers might fit into a particular
inventory. Bear in mind that these graphics are a guide only but nonetheless
provide an indication as to which sails might be used to cover a given range of
conditions and angles. Clearly a smaller inventory than those shown would
either leave more gaps or else mean that the remaining sails in the inventory
are having to do more work or are less than optimal. For example, removing the
S1.5 from the symmetric inventory doesn’t necessarily mean that the S2 can’t
cover the gap it would leave but it wouldn’t do as good a job. On the other
hand, if you want to sail at a TWA of 70° in 4kts TWS your only chance is to
fly a Code Zero, the other spinnakers simply won’t get you there! It is also
possible of course to have a mixture of symmetrics and asymmetrics onboard in
order to cover all the bases. At OneSails our design teams have experience of
designing custom sails for boats ranging from America’s Cup to the smallest of
One-Designs and it is this breadth of experience that means that we can offer
you the right advice and make sure that you get the right sails for your boat
and your specific needs. Please don’t hesitate to contact us to discuss all
your downwind requirements.